AppVeyor: Updated builds to Qt 6.8 (#4136)

Updated the image to 'Visual Studio 2022' since Qt 6.8 no longer ships
with binaries for VS 2019.

Updated to Qbs 2.4.1 to match the version used in GitHub Actions.

appveyor.yml

@@ -1,7 +1,7 @@
 clone_depth: 200
 version: '1.11.{build}'
 image:
-  - Visual Studio 2019
+  - Visual Studio 2022
 
 cache:
   - C:\Users\appveyor\.m2
@@ -12,15 +12,15 @@ environment:
   BUTLER_API_KEY:
     secure: j7JM5L6KeqpnQukzJLsm7J6oV92SpmyEZLSoED1pZ3gQ79VIkdxtbQmTkqUNZPsz
   matrix:
-    - QTDIR: C:\Qt\6.7\msvc2019_64
+    - QTDIR: C:\Qt\6.8\msvc2022_64
       PYTHONHOME: C:\Python312-x64
-      DEFAULT_PROFILE: MSVC2019-x64
+      DEFAULT_PROFILE: MSVC2022-x64
       PUSH_RELEASE: false
       ENABLE_ZSTD: false
-    - QTDIR: C:\Qt\6.7\mingw_64
+    - QTDIR: C:\Qt\6.8\mingw_64
       PYTHONHOME: C:\Python312-x64
-      MINGW: C:\Qt\Tools\mingw1120_64
-      DEFAULT_PROFILE: x86_64-w64-mingw32-gcc-11_2_0
+      MINGW: C:\Qt\Tools\mingw1310_64
+      DEFAULT_PROFILE: x86_64-w64-mingw32-gcc-13_1_0
       PUSH_RELEASE: true
       ENABLE_ZSTD: true
       TILED_ITCH_CHANNEL: windows-64bit
@@ -35,7 +35,7 @@ environment:
 configuration: Release
 
 install:
-  - choco install -y qbs --version 2.2.1
+  - choco install -y qbs --version 2.4.1
   - nuget install secure-file -ExcludeVersion
   - set PATH=%PATH%;%QTDIR%\bin;%MINGW%\bin